Hi everybody,
I'm currently using d8 (the standalone version of the v8), and I'm trying
to understand what's the meaning of the output when the flag --trace_opt is
on, and when the flag --trace_deopt is on, but I'm having some trouble to
fully understand it.
Here is the first part of the output, using the --trace_opt flag:
[disabled optimization for 0x1f065a249961 <SharedFunctionInfo SAR>, reason:
Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a248471 <SharedFunctionInfo ADD>, reason:
Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a249499 <SharedFunctionInfo BIT_AND>,
reason: Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a249bc9 <SharedFunctionInfo SHR>, reason:
Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a249241 <SharedFunctionInfo BIT_OR>,
reason: Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a2497c9 <SharedFunctionInfo SHL>, reason:
Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a248cb9 <SharedFunctionInfo MUL>, reason:
Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a249631 <SharedFunctionInfo BIT_XOR>,
reason: Call to a JavaScript runtime function]
[disabled optimization for 0x1f065a248a61 <SharedFunctionInfo SUB>, reason:
Call to a JavaScript runtime function]
[marking 0x2b5748934b69 <JS Function intAt (SharedFunctionInfo
0x2b574892f709)> for recompilation, reason: small function, ICs with
typeinfo: 4/5 (80%), generic ICs: 1/5 (20%)]
[compiling method 0x2b5748934b69 <JS Function intAt (SharedFunctionInfo
0x2b574892f709)> using Crankshaft]
My questions are:
1) Why does the first nine lines (all the disabled optimization lines) are
always printed? I can read that the reason is "Call to a JavaScript runtime
function", but does this mean that every runtime function optimization will
be disabled?
2) The following line (the one that starts with [marking...]) has "ICs with
typeinfo", "generic ICs" information besides the "reason" information, and
I guess this is the type information that was gathered by the full
compiler. But how is this information gathered? Is this done through the
profiler?
Below is a part of the output, using the --trace_deopt flag:
[deoptimizing (DEOPT soft): begin 0x2b8d27c35581 <JS Function bnpDivRemTo
(SharedFunctionInfo 0x2b8d27c30381)> (opt #8) @63, FP to SP delta: 208]
;;; deoptimize at 9660: Insufficient type feedback for generic
named access
reading input frame bnpDivRemTo => node=4, args=778, height=20; inputs:
0: 0x2b8d27c35581 ; (frame function) 0x2b8d27c35581 <JS Function
bnpDivRemTo (SharedFunctionInfo 0x2b8d27c30381)>
1: 0x329334048439 ; [fp + 40] 0x329334048439 <a BigInteger with map
0x99d6b605701>
2: 0x329334046041 ; [fp + 32] 0x329334046041 <a BigInteger with map
0x99d6b605701>
3: 0x34f71f04101 ; [fp + 24] 0x34f71f04101 <null>
4: 0x329334048439 ; [fp - 56] 0x329334048439 <a BigInteger with map
0x99d6b605701>
5: 0x2b8d27c04101 ; [fp - 24] 0x2b8d27c04101 <FixedArray[137]>
6: 0x34f71f041b9 ; (literal 7) 0x34f71f041b9 <undefined>
7: 0x34f71f041b9 ; (literal 7) 0x34f71f041b9 <undefined>
8: 0x3293340daf19 ; [fp - 64] 0x3293340daf19 <a BigInteger with map
0x99d6b605701>
9: 0 ; (int) [fp - 72]
10: 0 ; (int) [fp - 80]
11: 0x34f71f041b9 ; (literal 7) 0x34f71f041b9 <undefined>
12: 12 ; (int) [fp - 88]
13: 37 ; (int) [fp - 96]
14: 0x3293340daf49 ; [fp - 32] 0x3293340daf49 <JS Array[38]>
15: 0xa52619300000000 ; [fp - 48] 173171091
16: 0x34f71f041b9 ; (literal 7) 0x34f71f041b9 <undefined>
17: 1.550117e+00 ; (double) [fp - 200]
18: 5.774636e-09 ; (double) [fp - 208]
19: 0x1000000000 ; (literal 14) 16
20: 73 ; (int) [fp - 120]
21: 36 ; (int) [fp - 128]
22: 0x3293340db1e1 ; [fp - 136] 0x3293340db1e1 <a BigInteger with map
0x99d6b605701>
23: 0x329334048469 ; [fp - 144] 0x329334048469 <JS Array[75]>
24: 0x34f71f041b9 ; (literal 7) 0x34f71f041b9 <undefined>
translating frame bnpDivRemTo => node=778, height=152
0x7fff5fbff338: [top + 208] <- 0x329334048439 ; 0x329334048439 <a
BigInteger with map 0x99d6b605701> (input #1)
0x7fff5fbff330: [top + 200] <- 0x329334046041 ; 0x329334046041 <a
BigInteger with map 0x99d6b605701> (input #2)
0x7fff5fbff328: [top + 192] <- 0x34f71f04101 ; 0x34f71f04101 <null>
(input #3)
0x7fff5fbff320: [top + 184] <- 0x329334048439 ; 0x329334048439 <a
BigInteger with map 0x99d6b605701> (input #4)
0x7fff5fbff318: [top + 176] <- 0x256ebd920497 ; caller's pc
0x7fff5fbff310: [top + 168] <- 0x7fff5fbff358 ; caller's fp
0x7fff5fbff308: [top + 160] <- 0x2b8d27c04101 ; context
0x2b8d27c04101 <FixedArray[137]> (input #5)
0x7fff5fbff300: [top + 152] <- 0x2b8d27c35581 ; function
0x2b8d27c35581 <JS Function bnpDivRemTo (SharedFunctionInfo
0x2b8d27c30381)> (input #0)
0x7fff5fbff2f8: [top + 144] <- 0x34f71f041b9 ; 0x34f71f041b9
<undefined> (input #6)
0x7fff5fbff2f0: [top + 136] <- 0x34f71f041b9 ; 0x34f71f041b9
<undefined> (input #7)
0x7fff5fbff2e8: [top + 128] <- 0x3293340daf19 ; 0x3293340daf19 <a
BigInteger with map 0x99d6b605701> (input #8)
0x7fff5fbff2e0: [top + 120] <- 0x00000000 ; 0 (input #9)
0x7fff5fbff2d8: [top + 112] <- 0x00000000 ; 0 (input #10)
0x7fff5fbff2d0: [top + 104] <- 0x34f71f041b9 ; 0x34f71f041b9
<undefined> (input #11)
0x7fff5fbff2c8: [top + 96] <- 0xc00000000 ; 12 (input #12)
0x7fff5fbff2c0: [top + 88] <- 0x2500000000 ; 37 (input #13)
0x7fff5fbff2b8: [top + 80] <- 0x3293340daf49 ; 0x3293340daf49 <JS
Array[38]> (input #14)
0x7fff5fbff2b0: [top + 72] <- 0xa52619300000000 ; 173171091 (input
#15)
0x7fff5fbff2a8: [top + 64] <- 0x34f71f041b9 ; 0x34f71f041b9
<undefined> (input #16)
0x7fff5fbff2a0: [top + 56] <- 0x34f71f04359 ; 0x34f71f04359 <Odd
Oddball> (input #17)
0x7fff5fbff298: [top + 48] <- 0x34f71f04359 ; 0x34f71f04359 <Odd
Oddball> (input #18)
0x7fff5fbff290: [top + 40] <- 0x1000000000 ; 16 (input #19)
0x7fff5fbff288: [top + 32] <- 0x4900000000 ; 73 (input #20)
0x7fff5fbff280: [top + 24] <- 0x2400000000 ; 36 (input #21)
0x7fff5fbff278: [top + 16] <- 0x3293340db1e1 ; 0x3293340db1e1 <a
BigInteger with map 0x99d6b605701> (input #22)
0x7fff5fbff270: [top + 8] <- 0x329334048469 ; 0x329334048469 <JS
Array[75]> (input #23)
0x7fff5fbff268: [top + 0] <- 0x34f71f041b9 ; 0x34f71f041b9
<undefined> (input #24)
[deoptimizing (soft): end 0x2b8d27c35581 <JS Function bnpDivRemTo
(SharedFunctionInfo 0x2b8d27c30381)> @63 => node=778, pc=0x256ebd907e83,
state=NO_REGISTERS, alignment=no padding, took 0.360 ms]
Materialization [0x7fff5fbff2a0] <- 0x3293340db651 ; 0x3293340db651
<Number: 1.55012>
Materialization [0x7fff5fbff298] <- 0x3293340db661 ; 0x3293340db661
<Number: 5.77464e-09>
[removing optimized code for: bnpDivRemTo]
This is the output that I'm having more trouble to understand.
My question would be:
3) Could anyone roughly explain what this output means? The 24 numbers, the
hexadecimal numbers, with the [top + X] values, for instance. I understand
that at the end, it explains that there's some code removed for the
function.
Thanks for the help,
Ignacio.
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